Subterranean drilling typically involves a drill string having a bottom hole assembly provided with tools configured to perform a variety of functions. The tools are generally powered by drilling fluid pumped through the drill string. Some fluid driven drill string tools require a fluctuating amount of fluid over time. An example of such tool is a percussion hammer applied to drive a percussion drill bit. During part of the operational cycle of such percussion hammer the demand for fluid is higher than the time-average demand, while during another part of the cycle the demand is lower than the time-average demand. As a result thereof, the pressure across the tool also has a strong variation. During the part of the cycle of higher fluid demand the pressure across the tool is lower than the time-average, and during the part of the cycle of lower fluid demand the pressure across the tool is higher than the time-average. This variation of pressure is generally referred to as water hammer. It causes a reduction of drilling efficiency and potentially interferes with other drill string tools such as pressure-pulse based communication system.